1-Methylimidazolium hydrogen sulfate catalyzed convenient synthesis of 2,5-dimethyl-N-substituted pyrroles under ultrasonic irradiation

Ionic liquid [HMIM]HSO4 was found to be an efficient catalyst for the synthesis of N-substituted pyrroles through the reaction of 2,5-hexanedione with amines under ultrasonic irradiation at room temperature. These reactions proceed with good yields under short reaction time. Furthermore, the green catalytic system can be recycled specific times with no decreases in yields and reaction rates.

► Acid ionic liquid was used as catalysts. ► The products were synthesized using acid ionic liquid for the first time. ► The reactions were carried out under green catalyst conditions. The catalyst could be recycled and reused. ► Generality of the method, high yields and very short reaction times.